The present disclosure relates to synchronous motors. More particularly, the present disclosure relates to recovery from the loss of a field excitation unit for the motor.
When a synchronous motor loses its field excitation supply, it is either shut down or is operated in an asynchronous mode for the time that it takes to repair the field excitation supply. However, extended operation of the synchronous motor in an asynchronous mode can result in overheating, and requires an oversized motor and power system. Moreover, when operating in an asynchronous mode, a synchronous motor can normally only drive a reduced load vis-a-vis a full load when operating in a synchronous mode.
Accordingly, there is a need to solve the problem of how to recover from the loss of a field excitation supply of a synchronous motor so as to restore the motor to full load synchronous operation while minimizing the time running asynchronously or without resorting to asynchronous operation.